Porting newlib.

[Paul Chavent <paul dot chavent at free dot fr>]

Good morning.

I have some questions about porting Newlib. It seems that for a new 
platfrom support we typicaly need :
 - a linkscript (no deal with newlib, but with binutils/ld)
 - a start code and syscalls implementation (that must be provided for 
newlib).
 - some other thing ?


Moreover, your online doc on libc tells us to implement a minimum set of 
syscalls. For example _exit close etc...
In this doc, some function begin with an underscore and other not.
In the syscall.c and libcfunc.c (in the newlib/libc/sys/arm directory) 
it is explain :
  - Functions which begin with an underscore are in the system 
namespace and go in the syscall.c file.
  - Functions without leading underscore are in the C namespace and go 
in the libcfunc.c file.

I don't understand the difference between the system namespace and C 
namespace and my questions are :
 Are system namespace and C namespaces equivalent to user space and 
kernel space in the Linux kernel ?
 Which minimum syscalls should we provide : with underscore or without ?
 If we provide some underscore functions, should we provide the sames 
without underscore ?


Ok, a last thing : in the newlib/configure.host there is
  [code]
  arm-*-*)
	if [ "x${newlib_may_supply_syscalls}" = "xyes" ] ; then
	  sys_dir=arm
	fi
	;;
  [/code]
and in newlib/libc/sys/arm/Makefile.am :
  [code]
  if MAY_SUPPLY_SYSCALLS
  extra_objs = syscalls.o
  else
  extra_objs =
  endif
  lib_a_SOURCES = libcfunc.c trap.S
  [code]

The facts :
  If newlib may not supply syscalls, the sys_dir is not set and neither 
syscalls.c or libcfunc.c are used.
  If newlib may supply syscalls either syscalls.c and libcfunc.c are used.
The question :
  Is there any case where syscalls.c is used and libcfunc is not or the 
oposite ?


Thank you.

Paul.